Infections caused by fungi and yeast affect animals including humans, and plants worldwide. One type of fungus, Trichophyton metangrophytes causes ringworm. In addition, these organisms contaminate water and food supplies
Current methods to detect the presence of contaminating fungi and yeast require obtaining samples from an animal or plant suspected of containing these organisms and culturing the samples to grow any organisms present in the sample in sufficient numbers to readily detect their presence visually. Typically, culturing the organisms requires specialized and costly media and lengthy culture times of up to several weeks. Other methods involve the use of a hot basic solution such as 20% potassium hydroxide to clear smears of specimens on a solid substrate. The cleared specimen is then stained, for example using India ink, then examined by microscope to detect the presence of fungal structures remaining after this treatment.
Fungi and yeasts contain certain substances, including proteins that may be specific for a particular species. Other substances are more widely distributed. For example, chitin (N-acetylglucosamine oligomer) is a polysaccharide component of cell walls found in most fungi and yeasts and is reactive with reagents such as lectins (Galun et al., Arch. Microbiol. 108(1):9-16 (1976)).
Assays for the presence of chitin-containing organisms such as fungi are known but have been limited to the detection of chitin using chemical analyses including colorimetric determination (Sharma et al., Trans. Br. Mycol Soc. 69(3):479-83 (1977)) and the use of nitrous acid-3-methyl-2-benzothiazolinone hydrazone hydrochloride-ferric chloride and light microscopy (Kaminskyj et al., Can. J. Bot. 60(12): 2575-80 (1982)). Immunological assays to detect various microorganisms including fungi using antibodies are also known, including those employing monoclonal antibodies reactive with antigens associated with particular organisms. (Goldstein, European Patent Application EP 176,355 (1986)). Such assays are not widely applicable because they are based on species-specific proteins including antigens. In addition, to detect the organism the assays typically require that the specific protein be isolated or exposed for reaction with the antibody in the assay.
There continues to exist a need for rapid and reliable detection of fungi and yeasts without requiring in vivo or in vitro culturing techniques or complex staining reagents, and that is applicable to a wide variety of organisms. The present invention satisfies these needs and provides related advantages as well.